THE STUDY OF LONGITUDINAL AND LATITUDINAL VARIATION OF EQUATORIAL ELECTROJET SIGNATURE AT STATIONS WITHIN THE 96°MM AND 210°MM AFRICAN AND ASIAN SECTORS RESPECTIVELY UNDER QUIET CONDITION

THE STUDY OF LONGITUDINAL AND LATITUDINAL VARIATION OF EQUATORIAL ELECTROJET SIGNATURE AT STATIONS WITHIN THE 96°MM AND 210°MM AFRICAN AND ASIAN SECTORS RESPECTIVELY UNDER QUIET CONDITION

ABSTRACT

Solar quiet current (𝑆𝑞) and Equatorial Electrojet (EEJ) are two current systems which are produced

by electric current in the ionosphere. The enhancement of the horizontal magnetic field is the EEJ.

This research is needed for monitoring equatorial geomagnetic current which causes atmospheric

instabilities and affects high frequency and satellite communication. This study presents the

longitudinal and latitudinal variation of equatorial electrojet signature at stations within the

96°𝑚𝑚 𝑎𝑛𝑑 210°𝑚𝑚 African and Asian sectors respectively during quiet condition. Data from

eleven observatories were used for this study. The aim of this study is to investigate the equatorial

variation of the solar quite (𝑆𝑞) current, as well as determine the longitudinal and latitudinal

magnetic signatures on the EEJ at some African and Asian sectors under quiet condition. The

objectives of the study therefore are to: Determine the longitudinal and latitudinal geomagnetic field

variations during solar quiet conditions along the 96° 𝑎𝑛𝑑 210°𝑚𝑚; Investigate monthly variation

and diurnal transient seasonal variation; Measure the strength of the EEJ at stations within the same

longitudinal sectors of 96° 𝑎𝑛𝑑 210° 𝑚𝑎𝑔𝑛𝑒𝑡𝑖𝑐 𝑚𝑒𝑟𝑖𝑑𝑖𝑎𝑛; and find out the factors responsible for

the longitudinal and latitudinal variation of EEJ under solar quiet condition. Horizontal (𝐻)

component of geomagnetic field for the year 2008 from Magnetic Data Acquisition System

(MAGDAS) network were used for the study. The International Quiet Days (IQDs) were used to

identify quiet days. Daily baseline values for each of the geomagnetic element 𝐻, can be obtained

from 𝐻0 = 1

⁄2 (𝐻24 + 𝐻1) where 𝐻0 is the dailybaseline. The daily baseline was subtracted from

the hourly values to get the hourly departure from midnight for a particular day𝑑𝐻 = 𝐻𝑡 − 𝐻0 where

𝑡 = 1 𝑡𝑜 24 𝑎𝑛𝑑 𝑑𝐻 gives the measure of the hourly amplitude of the variation of 𝐻. The monthly

average of the diurnal variation was found. The seasonal variation of 𝑑𝐻 was found by averaging the

monthly means for Lloyd’s season. Results showed that: The longitudinal and latitudinal variation in

the 𝑑𝐻 differs in magnitude from one station to another within the same longitude due to the

difference in the influence of the EEJ on them, which depends on how far from or near (latitudinal

difference) they are to the EEJ band (confined within ±3° 𝑙𝑎𝑡𝑖𝑡𝑢𝑑𝑒) wherein the EEJ current flows

eastwards; The highest monthly longitudinal variation of EEJ is 92 𝑛𝑇 at DAV and TIR during

September equinox. This high amplitude at DAV and TIR compared with the other 9 stations, showed

the presence of higher electric current (equatorial electrojet) in the ionosphere flowing over DAV and

TIR. Thus the high magnitude could possibly be due to a greater width of the electrojet over the

stations. The variation pattern for daily, monthly and seasonal variation were found to be similar;

The magnitude of EEJ strength at stations within the same specified longitude differ where the EEJ

strength at ILR is maximum with 𝑑𝐻 of 55 𝑛𝑇 at about 1100 LT and maximum EEJ strength at DAV

is 93 𝑛𝑇 at about 1200LT which is the highest for the specified year; The possible factors responsible

for the variation of EEJ is seen to be the ionospheric processes and physical structure such as wind

and conductivity. The 𝑑𝐻 value peaks between 1000 LT and 0200 LT for all the plots and varies with

longitude and with latitude. The EEJ value for equinoctial months is seen to be higher than those of

solstice months where the buildup flank is steeper in the morning hours than in the evening hours.

TOPIC: THE STUDY OF LONGITUDINAL AND LATITUDINAL VARIATION OF EQUATORIAL ELECTROJET SIGNATURE AT STATIONS WITHIN THE 96°MM AND 210°MM AFRICAN AND ASIAN SECTORS RESPECTIVELY UNDER QUIET CONDITION

Chapters: 1 - 5
Delivery: Email

Number of Pages: 68

Price: 3000 NGN

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